'Trojan cells' treat brain diseases from the inside

时间：2019-03-02 07:11:05166网络整理admin

By Gaia Vince Scientists have managed to protect and regenerate the part of the brain that is damaged in Parkinson’s disease, by genetically engineering cells to bypass the blood-brain barrier. The study was conducted in animals, but the approach could one day be used to treat brain conditions in humans, the researchers say. The blood-brain barrier protects the brain from harmful substances, but also prevents drugs from entering, so experimental treatments have involved injecting drugs directly into the brain. Now Clive Svensden at the University of Wisconsin-Madison, US, and colleagues have devised an alternative – implanting cells that act as a Trojan horse, churning out the drug from inside the brain’s fortress. The team took human neural progenitor cells (hNPCs) from fetal tissue at 10 to 15 weeks’ gestation. These have a lot in common with stem cells, though they have already differentiated into specific neural cells. The researchers genetically modified the cells to produce a growth molecule called glial cell line-derived neurotrophic factor (GDNF). This is produced naturally by the brain at around eight weeks’ gestation in humans, but by 20 weeks it has all gone. Previous studies show that GDNF increases the survival and function of dopamine-producing cells, which are progressively destroyed in Parkinson’s disease. Symptoms of the disease were induced in rats and monkeys by destroying 70% of the animals’ dopamine-producing cells on one side of the brain. Ten days later, the genetically engineered hNPCs were injected into a region of the animals’ brains called the striatum. After five weeks, there was a noticeable difference in the brains of the animals that had received the treatment compared with controls. “Not only had the cells been producing GDNF like a mini-pump’, but the protective molecule had migrated in the brain to the substantia niagra, where the dopamine-releasing neurons are located,” Svendsen says. “This caused the neurons to start sprouting new processes and release dopamine.” The effect lasted for three months. Seth Love, a neurologist at Bristol University in the UK, who has experimented with injecting GDNF into the brains of Parkinson’s patients, says the study is promising. “Using progenitor cells is a great advance and should reduce any immune response and allow for more biologically active GDNF,” he told New Scientist. Kieran Breen, director of research at the Parkinson’s Disease Society, UK, is optimistic but cautions that the technology is at an early stage of development. “The issue is the ability to control the amount of GDNF produced, once the stem cells have been introduced into the brain,” he says. Journal reference: Gene Therapy (DOI: